离心风机吸声蜗壳结构的数学物理模型及实验验证

Mathematical-Physical Model of Noise-Absorbing Volute of Centrifugal Fan and Experimental Validation

为了降低离心风机气动噪声,设计了一种由穿孔蜗板、吸声材料、微穿孔板和空腔组成的吸声蜗壳结构,并采用声电类比方法建立了吸声蜗壳的数学物理模型.基于该模型分析发现:采用一定厚度的吸声材料可以在大约1～8kHz频率范围内对气动噪声取得较好的吸声效果,适当增加吸声材料厚度可使得具有较高吸声系数的频率范围向低频方向适当拓宽,加之再增加一定的空腔厚度可以提高某低频离散噪声的吸收效果.计算得出的降噪量和吸声系数的变化趋势基本一致,且随着声波在固体表面反射次数的增加,降噪量逐渐增加并趋于6dB.对不同工况和吸声结构尺寸下的离心风机进行了多次实验测量,结果印证了所提模型的适用性.该模型可以作为所提结构吸声蜗壳进行优化设计时的辅助计算工具.

To reduce the aerodynamic noise of centrifugal fans, a mathematical-physical model was established to analyze the property of the sound-absorption volute of a centrifugal fan, which is composed of a perforated volute plate, an acoustic-absorbing liner, a micro-perforated plate and a cavity. The analysis with this model indicates that the absorbing liner of certain thickness would yield fine effect absorbing aerodynamic noise of about 1-8 kHz. The frequency range with higher coefficient values would be widened towards the direction of low frequency with the increase in liner thickness. Further application of cavity presents better effect absorbing tonal aero- dynamic noise of a low frequency within a narrow range. The theoretical amount of noise reduction shows a similar tendency to that of sound-absorption coefficient, and increases with the in- crease in the number of wave reflections. The noise reduction rises gradually to a constant value of about 6dB. Experimental results of multiple tests on the centrifugal fan with this sound- absorption volute for different operation conditions and geometry configurations are consistent with the predictions by the present model.